Answer:
Phospholipid Bilayer
Step-by-step explanation:
The cellular phospholipid bilayer has 2 layers of phospholipids(obviously), but keep in mind that the heads of said phospholipids are hydrophillic(loving water) and the tails are hydrophobic(hating water). This makes the 2 layers line up with heads facing away from each other and tails facing each other. This is so the bilayer can exist in the aqueous enviorment outside the cell as a barrier and inside the aqueous enviorment of the cell to transport materials in and out of the cell.